METHOD FOR PRODUCING HIGH-PURITY BORON NITRIDE SINTERED COMPACT HAVING HIGH HARDNESS AND HIGH TOUGHNESS

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a high-purity boron nitride sintered compact, which is low in cleavage property, is excellent in crack propagation suppressing action and includes high hardness and high toughness.

SOLUTION: The high-purity boron nitride sintered compact containing a trace quantity of wurtzite type boron nitride is produced by cleaning the surface of fine wurtzite type boron nitride powder having ≤0.5 μm particle diameter with a supercritical fluid containing no oxygen and using solid polyvinylidene chloride, polyvinyl chloride and polyethylene as fluid sources and sintering under a high-pressure high-temperature condition of ≥5 GPa and ≥1,400°C without adding a sintering aid.

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